Fuel vapors generated during refueling events may, in some examples, be adsorbed into an onboard refueling canister configured to store fuel vapors from refueling and diurnal engine operations. In other examples, refueling vapors may be recovered offboard into an underground tank at a gas station.
For vehicles configured to adsorb refueling vapors via an onboard refueling canister, the canister may be sized to adsorb refueling, running loss, hot soak, and diurnal cycle vapors. In such an example, refueling vapors may determine the bulk of the canister size, as refueling vapors may represent the largest fraction of total vapors adsorbed by the canister. An example of such a system is referred to as onboard refueling vapor recovery (ORVR). For ORVR vehicle systems, fuel vapor adsorbed into the onboard refueling canister is subsequently drawn from the canister into an engine intake manifold (under intake manifold vacuum conditions) for combustion with the normal fuel and air mixture, in a process referred to as purging.
For vehicles configured to recover refueling vapors into an underground tank at a gas station, the canister may be much smaller, as refueling vapors are recovered by the gas station infrastructure. In such an example, specially designed refueling nozzles with boots that seal around a fuel filler neck may route refueling vapors into an underground tank where the vapors are condensed. Such an example is referred to as non-ORVR.
Vehicles on the road may be a mixture of ORVR and non-ORVR. Similarly, gas stations may be configured for either offboard recovery, or onboard recovery. If a vehicle with an ORVR system refuels at a station with offboard recovery capabilities, and no mitigating actions are taken, a number of undesirable outcomes may result. For example, in attempting to route fuel vapors to an underground storage tank, while the vehicle is configured to route fuel vapors to an onboard storage canister, energy may be wasted, wear and tear of the offboard system may be increased, and an excess of air may be ingested into the underground storage tank, which may result in undesired pressure buildup due to the expanded volume of hydrocarbon saturated air.
Toward this end, U.S. Pat. No. 5,992,395 teaches detecting a vehicle having an ORVR system during refueling by monitoring for the presence of hydrocarbon vapors in a vapor recovery path to an underground storage tank. In such an example, an absence of detected hydrocarbon vapors may indicate the presence of an ORVR system in the vehicle being refueled. Responsive to indicating that the vehicle being refueled includes an ORVR system, the dispenser may deactivate the offboard vapor recovery system, or may redirect the air flow in the vapor recovery path to atmosphere.
However, the inventors herein have recognized potential issues with such an approach. For example, for a vehicle with an ORVR system, including a canister sized to capture refueling vapors, the canister may be unnecessarily loaded during refueling at a gas station with offboard fuel vapor recovery infrastructure. More specifically, vehicles such as hybrid electric vehicles (HEVs), and start/stop (S/S), may spend considerable time in electric-only driving mode. Because purging of the canister relies on intake manifold vacuum, purging of the canister may not be conducted during electric-only driving mode. For such vehicles, unnecessary loading of the canister may contribute to a risk of hydrocarbon breakthrough from the canister to atmosphere.
Thus, the inventors herein have developed systems and methods to at least partially address the above issues. In one example, a method is provided, comprising during refueling a fuel tank of a vehicle at a gas station, routing fuel vapors from the fuel tank to a fuel vapor storage canister positioned in an evaporative emissions system that is removably coupled to the fuel tank; and during the refueling, adjusting a rate of the routing fuel vapors to the canister responsive to an indication of a vehicle offboard fuel vapor recovery infrastructure at the gas station.
As an example, adjusting the rate of routing fuel vapors from the fuel tank to the fuel vapor canister may include decreasing the rate of routing fuel vapors from the fuel tank to the fuel vapor canister responsive to the indication of the offboard fuel vapor recovery infrastructure, as compared to a condition where offboard fuel vapor recovery infrastructure is not indicated. Responsive to adjusting the rate of routing fuel vapors from the fuel tank to the fuel vapor storage canister, a greater portion of refueling vapors may be directed to the offboard fuel vapor storage infrastructure, than to the fuel vapor storage canister. In this way, loading of the fuel vapor canister may be reduced which may prevent undesired bleedthrough emissions resulting from a canister loaded with fuel vapors, particularly in examples where the vehicle is a hybrid vehicle and where engine runtime is limited.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.